Dear visitor, welcome to SPRINKLER TALK FORUM - You Got Questions, We've Got Answers. If this is your first visit here, please read the Help. It explains how this page works. You must be registered before you can use all the page's features. Please use the registration form, to register here or read more information about the registration process. If you are already registered, please login here.

I'm not exactly sure which valve that is. A picture would help.
If the 1" Irritrol 100 valve pictured below looks like it'll work then you'll either need to buy a whole new valve and harvest parts or buy a retro-fit kit. You wont be able to use your old diaphragm with a new bonnet. They're double beaded now. I'm assuming you mean the top half of the valve from what you've stated in your post